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I have installed Centos 6 on a virtual machine (virtualbox). Maximum available screen resolution is 800x600. How do I get higher resolutions?

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This might be a bug in CentOS 6. Look at the release-notes for RedHat 6.1 regarding problems with 800 x 600. – Nils Nov 13 '11 at 20:58
up vote 2 down vote accepted

Install the VirtualBox Guest Additions in the virtual machine. You can do this by selecting "Install Guest Additions" from the Devices menu. This will install a device driver into the guest OS that will dynamically adjust the screen resolution as you resize the VirtualBox window.

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Thanks. I had edited xorg.conf file under /etc/X11 to get custom resolutions. I had added 1920x1080. When I rebooted, it couldn't start X window. Then I entered rescue mode and deleted xorg.conf file. Because I read that it creates a default xorg.conf file if it is deleted. I rebooted again, X window started, but there were no xorg.conf file under /etc/X11. Why wasn't it created? And, isn't this file necessary for X window to start? Why didn't the absence of xorg.conf result in any errors? – alwbtc Nov 10 '11 at 5:18
One of the recent versions of xorg eliminated the need for xorg.conf. You only need xorg.conf now if the default settings guessed by xorg are not to your liking. – cantfork Nov 21 '11 at 2:02

You need Virtual Box guest extensions.

In order to install them you first need the RPMForge repository added for yum, follow these instructions:

Then run this command in a terminal:

yum install dkms
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thank you so much @Beachhouse Sir.. work like charm for me.. i am using CentOS 6.5 – Muhammad Sufiyan Apr 9 '14 at 0:04

VirtualBox Guest Additions includes the screen drivers for auto-resizing.

I find I occasionally need to rerun the GuestAdditions after installing software, and frequently so after doing a system update. Following re-install of GuestAdditions, auto-resizing still unavailable until I do a system restart on the guest. Then auto-resize is available again.

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